ATP-3-09-30 Observed Fires Download
Page 126 of 204
Chapter 5 5-42 ATP 3-09.30 28 September 2017 Lasing Method 5-125. The observer can use a lasing device to measure the distance the target moves during a certain time interval. As the target moves, the observer lases it and converts the polar data to grid locations for points A and B. Then the observer determines how far the target moved by measuring the distance between points A and B and rounding to the nearest one meter. The observer divides the distance traveled by the time interval between points A and B to determine the target speed in meters per second. Reticle Pattern Method 5-126. This method works best when the target is moving across the observer's field of view. The observer can use the reticle pattern in any device with a reticle pattern graduated in mils to measure the distance the target moves during a certain time interval. As the target moves across the reticle pattern, the observer measures the number of mils traveled to the nearest 5 mils, then multiplies that number by the observer-target factor to convert the distance traveled by the target to meters. The observer divides the distance traveled by the time interval to determine the target speed, in meters per second and then rounds to the nearest one meter. The reticle pattern method does not work if the target is moving directly toward or away from the observer Note. The observer can also designate, by using a lasing device or binoculars, a distance on the ground, for example, 100 meters, then times how long the target takes to travel that distance and divides that distance by the time interval. Laser Range Method 5-127. This method works best when the target is moving directly toward or away from the observer. The observer can use a laser rangefinder to determine the range to points A and B. The observer must first determine and record the range to A. When the vehicle reaches point A, the observer tracks the vehicle for a specified time interval. When the time interval has passed, the observer lases the target to determine range (range at point B). Subtracting the smaller range from the larger range will give the distance between A and B. The observer now knows how far the vehicle moves during the specified time interval. The laser range method does not work if the target is moving across the observer's field of view. PREDICT THE INTERCEPT POINT 5-128. Once the observer determines the speed and direction of the target, the intercept point (grid) at which to engage the moving target must be predicted (see figure 5-21 on page 5-37). To do this, the observer first gathers and adds the following information: Total processing time, in seconds (observer, fires cell, FDC and gun times). Time of flight (estimated based on previous fire missions or by request upon establishment of the Observation Post). 5-129. The observer then multiplies that sum by the target speed. The product is the minimum distance to plot the intercept point in front of the moving target in the direction it is traveling. So the target will not pass the intercept point before the round impacts, the observer must plot the intercept point distance well ahead of the moving target to allow enough time to get the grid and prepare the call for fire. Experience dictates how far ahead of the target to plot the intercept point. An inexperienced observer should add to the intercept distance half the distance determined to allow enough time. To simplify plotting, the observer can round up the intercept distance to the nearest 100 meters.